A brief history of time(shifting) in the TV universe

I was looking for answers to the mysteries of our expanding TV universe: Why are there so many shows about time travel? Why are there so many shows, period, and does anyone have time to watch them all? In the age of DVRs and binge-watching, do time slots still exist, or are they just a delusion?

So I picked up Stephen Hawking's A Brief History of Time, hoping to find something smart to say about the changing ways in which TV interacts with the fourth dimension - time.

Appearances on The Simpsons, Star Trek: The Next Generation, and The Big Bang Theory cemented the Cambridge cosmologist's reputation as one of television's coolest guest stars, but other than reminding me that there are bigger questions out there than what to watch on TV, Hawking wasn't much help.

His chapter on worm holes and time travel, though, probably should be required reading for the characters in Timeless (10 p.m. Mondays beginning Oct. 3, NBC) and Frequency (9 p.m. Wednesdays beginning Oct. 5, CW), just two of the new series that will be messing around with the past, present, and future this season, with the usual potentially disastrous results.

In Timeless, a history professor (Abigail Spencer, Rectify) is sent back in time with a soldier (Matt Lanter, 90210) and a scientist (Malcolm Barrett, The Hurt Locker) to try to stop a villain (Goran Visnjic, ER), who's out to destroy America.

Frequency, inspired by the 2000 film about a son's connecting with his long-dead father through ham radio, is the story of a father (Riley Smith) and daughter (Peyton List) reaching across time to try to change a tragic past.

We already have Starz's Outlander - based on Diana Gabaldon's best-selling novels about a 20th-century Englishwoman married to an 18th-century Scotsman - as well as the CW's Legends of Tomorrow, Fox's Sleepy Hollow, Syfy's 12 Monkeys, and Hulu's Stephen King mini-series 11.22.63.

Come midseason, expect ABC's Time After Time (inspired by the book and movie in which H.G. Wells pursues Jack the Ripper) and the Fox comedy Making History, which stars Adam Pally (Happy Endings) as a professor whose time machine allows him to date Paul Revere's daughter (Leighton Meester, Gossip Girl).

And, of course, there's the long-running Doctor Who, now on its 12th Time Lord.

Shawn Ryan (The Shield), who revisits the 1937 Hindenburg disaster in the Timeless pilot he wrote with cocreator Eric Kripke (Supernatural), has gotten a lot of questions about the upswing in TV time travel.

"I've come up with two words: nostalgia and regret," he said in an interview last month.

"Nostalgia, the idea that I've missed something, that I miss how things used to be, and we're seeing some of that right now in the presidential election, from one candidate who's saying, 'Make America great again.' What America are we talking about? What time period are we talking about? Who was it great for? Who was it not so great for?" he said.

"And the regret - I think we've all had experiences, I know I certainly have, where I've done something or said something and either immediately or shortly thereafter, I've said, 'I wish I could go back and change that,' " Ryan said.

"There's something about time travel that I think hits us instinctually as a very appealing concept, because we all have things that we would change if we could."

But could we, assuming time travel existed, change the past? Countless movies and TV shows suggest we can't - or not, at least, without screwing up the present. (Hawking, too, outlines some of the arguments against it.)

Time-travel fans believe in rules, Ryan has learned.

"I've made a couple of cop shows, and viewers never seem to care if you take artistic license to compress time. You know, cases get investigated and wrapped up in a day, whereas they usually, in real life, take weeks and months," he said.

"You deal with time travel, and for a science that doesn't actually exist in the world, everybody has really strong opinions about how it would work, what the rules are - and I think they're accepting of whatever rules you give them, but they're going to hold your feet to the fire that you live by those rules."

Years ago, Outlander's Gabaldon, who was a scientist before she became a novelist, published her own rules, "The Gabaldon Theory of Time-Travel," in the Journal of Transfigural Mathematics. Not on my reading list, but reportedly she leaves her characters free to change the future.

One of the season's most anticipated shows, NBC's This Is Us, premiered Tuesday, and (spoiler alert) if you haven't yet seen it, you might want to skip ahead a couple of paragraphs.

Because the big twist at the end of Dan Fogelman's intricately woven pilot is that Milo Ventimiglia and Mandy Moore are playing the parents of the other three adults - played by Sterling K. Brown, Chrissy Metz, and Justin Hartley - and that the show takes place in both the past and the present.

Expect that to continue, as Ventimiglia and Moore's characters explore different points of their family's past.

Era-hopping isn't the only way TV's playing with our concept of time.

If you've ever sat down to watch a 10 p.m. drama and looked down as the credits rolled to find it was 11:15 or 11:30, you know that certain basic cable dramas - yes, I'm looking at you, Mr. Robot - treat their time slots as though they were made of rubber.

The argument that their streaming competitors can go as long - or as short - as they wish is good, as long as you're not the person who has to get up the next morning.

Because no one has yet invented an alarm clock that can turn back time.

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